May I cross closed gates in Iceland?

I've found looking in Google Street Map that in Iceland sometimes you find gates in public roads like this. In my country (Spain) these are very rare, but when they exist is because there are free cattle or something similar and you can open, enter and close the door if it's closed. In Iceland it's the same? Or they are used to close forbidden roads? (i.e. because there is too much snow and is impassable).